Hot air circulation device of tunnel kiln

The utility model discloses a hot air circulation device of a tunnel kiln. The hot air circulation device solves the problems of low product pass percent and low overall heating efficiency of a furnace due to the fact that refractory materials are not evenly heated. The hot air circulation device is characterized in that a hot air circulation fan (9) is arranged on the furnace top of a preheat section of the tunnel kiln, circulation air ducts (13) are arranged on the two sides of a hearth, an air hood (8) is arranged on the top of the hearth, a air suction opening formed in the top of the air hood (8) is connected with an air inlet of the circulation fan (9), an air distributing plate (11) is arranged at the bottom of the air hood (8), and a hot air pipeline (7) is arranged in the air hood (8). The hot air circulation device has the advantages of being even in heating, easy to control in temperature, good in product quality, and the like. Fire nozzles are omitted, gas consumption is reduced, work efficiency is improved, the firing pass percent of products can be 99%, and energy is saved by 38%.